This invention relates to a fuel injector, particularly to the construction of the injector nozzle.
In a known type of fuel injector, the nozzle comprises a single thin orifice disc out of which the fuel is emitted. Within the nozzle, just upstream of the single thin orifice disc, is a valve seat member having a centrally located seat and hole for a needle that is operated by the injector's solenoid to open and close the hole. The needle is guided by means of a needle guide member that is assembled concentrically to the valve seat member. The needle guide member contains straight holes spaced outwardly of its needle guide hole, and these straight holes provide for the passage of fuel through the needle guide member. In this type of injector, the single thin orifice disc controls the static fuel flow because almost all the pressure drop occurs across it. Additionally, fuel atomization is enhanced since velocity is proportional to the square root of the pressure drop across the orifice. A further attribute of this type of fuel injector is that it is generally lift-insensitive. The typical fuel spray pattern from the valve is mostly a thin column that is surrounded by a fine cloud around the outside.
It has now been discovered that the spray pattern can be enhanced without sacrificing the aforementioned advantages of a single thin orifice disc injector. This is accomplished by making the fuel holes in the needle guide member skewed instead of straight. As fuel passes through the skewed holes, angular momentum is imparted to it. Even though the diameter of the metering orifice in the single thin orifice disc is much smaller in diameter than either the diameter on which the skewed holes lie or the diameter of the hole through the valve seat member, there is a significant angular momentum in the fuel that passes through the metering orifice so that the column of fuel that exits the nozzle has significantly increased divergence. The amount of divergence is a function of the specific design. This type of a spray pattern will generally be advantageous when the injector is used to spray fuel toward the intake valve of an internal combustion engine. Yet the injector requires no more parts than the known injector described above.
The foregoing features and advantages of the invention, along with additional ones, will be seen in the ensuing description and claims, which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode presently contemplated for carrying out the invention.